Cable stripping tool

ABSTRACT

A manually held and manually operated tool for stripping the insulation from large diameter electric cables. The tool includes a member for supporting a range of different diameter cables in the tool while permitting rotation of the tool relative to the cable. The tool includes an insulator cutting blade whose depth of cut may be selectively varied and whose angular disposition relative to the cable may be selectively changed so as to permit the cutting of a spiral track through the insulator without the application of any axial pressure and which likewise permits the ends of the track to be squared.

United States Patent 3,665,603 Bilbrey et al. 1 May 30, 1972 CABLE STRIPPING TOOL FOREIGN PATENTS OR APPLICATIONS [72] Inventors: Robert A. Bilbrey, 21 Monte Vista, Orin- 1,294,484 4/1962 France ..30/90.7

da, Calif. 94563; Robert V. Van Gelder, 2739B Fulton Street, Berkeley, Calif.

Primary Examiner-Robert C. Riordon Assistant Examiner-Roscoe V. Parker, Jr. Att0rney-Harris Zimmerman [57] ABSTRACT A manually held and manually operated tool for stripping the insulation from large diameter electric cables. The tool includes a member for supporting a range of different diameter cables in the tool while permitting rotation of the tool relative to the cable. The tool includes an insulator cutting blade whose depth of cut may be selectively varied and whose angular disposition relative to the cable may be selectively changed so as to permit the cutting of a spiral track through the insulator without the application of any axial pressure and which likewise pennits the ends of the track to be squared.

l2 Clairm, 4 Drawing Figures PATENTEDMAYBO m2 3. 665,603

FIG F FlG 2 INVENTORS' ROBERT A. BILBREY BY ROBERT V. VAN GELDER ATTORNEY CABLE STRIPPING TOOL BACKGROUND OF THE INVENTION The stripping of insulation from electrical conduits does not present any serious problem when dealing with small diameter cables, since a simple knife operation is sufficient to cut through the relatively thin insulating coating to expose the conductor. However, in dealing with high voltage lines, the cable diameter may be up to about 2 inches, and the insulation may be about one-half inch thick and composed of relatively hard layers of different insulating materials. In removing such insulation, care must be taken to avoid nicking of the conductor, and mechanical devices heretofore available for stripping cable possess a number of shortcomings. By way of example, such prior art devices are not capable of accommodating different size cables without special adaptors or the like, they require excessive force applied by the operator, and are incapable of producing a combination of straight circular cuts and spiral cuts through the insulation.

SUMMARY OF THE INVENTION In accordance with the teachings of the present invention there is provided an extremely simple tool which is adapted to operate on a wide range of cable diameters without the requirement of any special adaptors or other specific diameter devices. Also, the instant tool is provided with a knife blade for cutting through the insulation which is not only capable of penetrating the insulation to any desired depth but which is angularly adjustable so that straight circular cuts may be made at one or both ends of the adjacent insulation and a uniform spiral cut made in the portion of the insulation to be stripped from the conductor. The slope of the helical or spiral cut may be easily changed so that the unwinding of the spirally cut material may be facilitated. Thus, for very heavy insulation the adjacent helical cut portions may be brought closer together, minimizing the subsequent force required to peel the cut material.

DRAWING FIG. 1 is a perspective view of the tool of the present invention with a cable operatively positioned therein;

FIG. 2 is an end elevational view of the tool;

FIG. 3 is a side elevational view of the tool, partly in crosssection; and

FIG. 4 is a plan cross-sectional view taken substantially in the plane indicated by line 4-4 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The tool of the present invention, generally indicated by the numeral in the drawing, and as above mentioned, is designed to remove or strip the insulation 12 from the conductor 14 of large diameter cable 16. The cable may have a diameter of from about if; inch to 2 inches, and as will be understood, the insulation provided on such cables may include a number of annular layers of insulating and protective materials, frequently of substantially greater cross-sectional extent than that of the conductor itself, and with the materials including rubber, light metal shielding, polyvinyl chlorides, synthetic elastomers and the like possessing different degrees of cutting resistance.

In broad terms, the tool 10 includes a manually engageable handle 18, means 20 for supporting the cable 16 in a rotatably clamped condition, and a knife holding assembly 22. As will which extends through the handle and into the assembly 22. A carrying ring 22 may also be provided at the upper distal end of the handle.

It will be noted that the assembly 22 extends laterally outwardly from the handle, and intermediate the assembly and the handle grip portion 26 there is provided a block 34 slidably mounted on the handle for longitudinal movement therealong. The block 34 has a handle receiving bore of the same cross-sectional configuration as the handle permitting such movement, and preferably both the handle and bore have other than a circular shape so as to prevent any movement other than the aforesaid longitudinal movement. Carried on block 34 is a portion of the cable support means 20, and as here shown, such means includes a V-shaped saddle 36 having an included angle of about on which the cable 16 may be positioned. The saddle extends laterally outwardly from the handle in parallel subjacent relation to the assembly 22 and the lower surface of the latter is provided with a planar cable engaging shoe element 38 adapted to overlie an upper lineal line portion of the cable when the latter is seated on the saddle. Such element is preferably formed of a low friction resistance material, such as tetrafluorethylene, and as best shown in FIG. 2, the upper walls of the saddle are likewise provided with similar shoe elements 40 and 42 which likewise engage the cable in lineal line contact.

To accommodate different size cables, the block 34 may be moved downwardly on the handle, the cable inserted between the upper cable engaging element 38 and the lower elements 40 and 42, and the block is then moved upwardly until the cable is firmly grasped therebetween. Then, by means of a set screw 44 extending through the block, the latter, together with the saddle, may be locked relative to the handle and knife assembly. As will be understood, this arrangement permits the reception of a wide range of cable diameters, insures proper clamping of the cable in the tool, but still permits rotation of the entire tool relative to the cable, due to the three line lineal contact provided by the cable engaging elements 38, 40 and 42. It should also be understood that in place of such engaging elements, rollers might be provided, but this would add to the complexity and cost of the tool.

Referring now to the knife holding assembly 22, it will be seen that the laterally extending cable engaging element 38 underlies a generally rectangularly shaped housing 46, and the end of the housing adjacent the handle 18 is provided with a bore 48 having its axis overlying and intersecting the internal apex 50 of the saddle. A bushing 52 is joumalled in said bore and is provided with an axially extending lug 54 along an interior wall thereof. A slider rod 56 is secured to the bushing adjacent said lug and extends radially outwardly from the bushing generally along the length of the housing 46. The latter, adjacent bore 48, has an opening 58 communicating with the bore and extending to the other end of the housing, a cover plate 60 overlying the same. The rod 56 extends from the bushing to such other end of the housing through the opening 58 and is thus capable of swinging movement in a plane parallel to the axis of the cable 16 positioned in the tool, but limited in arcuate extent by the width of the opening as best indicated in FIG. 4 of the drawing. The distal portion of the rod extends through a guide block 62 which moves along an arcuate track 64 provided on the housing, the lower end of the block slidably engaging a shoulder 68 provided on the housing. The rod has a manually engageable knob 70 at its distal end, and the inner end thereof is threadably connected to the bushing 52 and/or the lug 54 thereof. By loosening the knob 70, the rod, and consequently the bushing and its associated lug may be freely rotated in the housing bore to the extent provided for by the width of the opening 58. However, by tightening the knob, the guide block will be forced against shoulder 68 and the bushing lug will thus be locked in selective positions of rotational displacement. As will be later explained, such lug positioning will determine the angular disposition of the knife blade 24 relative to the cable.

Positioned within the bushing is a generally cylindrical knife holding element 72 provided with a radial slot 74 in which the blade 24 is positioned. A set screw 76 or other fastening means is provided to releasably secure the blade in the element. A second slot 78 is provided in the element 72 which interfits with the bushing lug 54 so that a rotation of the bushing as above described will produce a similar rotation of the element 72 and the knife blade 24 contained therein. The upper portion of element 72 is threaded as indicated at 80, and engageable therewith is an internally threaded blade depth control knob 82. The knob is provided with a circumferential groove 84 on a radially reduced portion 86 thereof, the knob shoulder 88 resting on the upper end portion of the housing. The latter is provided with a corresponding circumferential groove 90, and the knob is retained against axial displacement by means of a retainer lug 92 which is a bifurcated element insertable into the grooves 84 and 90. In this manner, as the knob is rotated, but prevented against axial movement, the element 72 with the knife blade attached thereto will move upwardly or downwardly relative to the space defined by the cable supporting shoe elements from an inoperative position out of such space to the operative position illustrated in the drawing.

In operation, the tool is moved onto the cable 16, and the block 34 is tightened on the handle when the shoe elements 38, 40 and 42 are clamped about the cable. Prior to insertion of the cable, the knob 82 is rotated so that the blade 24 is in a raised position. The blade is provided with a leading cutting edge 94 and a lower end 96 which slopes slightly upwardly from such edge. If a typical end strip operation is being perfonned, which provides for the conductor extending past the end of the insulation, as shown on the left portion of the cable illustrated in FIG. 1, the knife blade is positioned adjacent the end of the insulation 12 by rotation of knob 82, and the knob 70 and its associated rod 56 is rocked so that the blade receiving slot 74 and the blade therein is moved to an angular position. In other words, the blade may be moved between a first position wherein it is generally normal to the axis of the cable and a plurality of other positions wherein it is angularly related thereto. With the blade placed against the insulation and in an angular disposition, the operator, by engaging the handle 18 may rotate the tool about the cable in a clockwise direction as viewed in FIG. 2, and the blade 24 will carve a spiral path 98 through the insulation. When the desired length has been cut, the rod 56 is moved to one end of its travel which repositions the knife blade to its first normally related position to the cable so that further tool rotation about the cable produces a simple circular cut 100 transverse to the axis of the cable. The blade is then raised clear of the cable by rotation of knob 82 and the tool removed by lowering the saddle 36. The convoluted cut insulation is then peeled off.

With this construction, it will be appreciated that a T cut as illustrated in F IG. 1 may be made. Here, the initial cut is circular, with the blade normal to the cable and urged into the insulation by rotation of knob 82; the blade is then angled to produce the spiral cut; and the blade then returned to the finished circular cut. Removal of the thus cut insulation will lay bare the conductor 14 with insulation appearing on both sides thereof. If desired, and particularly in connection with blind cuts such as for a T, the knob 82 may be provided with a clicking detent and/or a depth measuring scale so that the amount of blade penetration through the insulation may be more readily determined.

We claim:

1. A tool for removing insulation from an insulated conducmoving said blade in a linear direction along the blade length, and for locking said blade in selected depths of insulation penetration, means in said assembly for changing the angular disposition of said blade about an axis defined by said lineal blade movement independent of said linear blade moving and locking means and while said blade is engaged with the insulation, and means in said assembly for locking said blade in selected positions of angular disposition.

2. A tool as set forth in claim 1 in which means are provided for selectively moving said elements from and towards each other for accommodating different diameter cable sizes.

3. A tool as set forth in claim 1 in which said elements include a plurality of angularly related planar surfaces extending generally normal to said blade.

4. A tool as set forth in claim 3 in which a pair of said surfaces defines a generally V-shaped configuration and another of said surfaces overlies the same and has an end portion terminating inwardly of the corresponding end portions of said pair of surfaces, and said blade extending downwardly from adjacent said first mentioned end portion in overlying relation to said corresponding end portions.

5. A tool as set forth in claim 1 including a manually engageable handle extending longitudinally from said cable engaging means in general parallel relation to said blade, at least one of said elements being carried on said handle for movement therealong, and means for releasably securing at least one of said elements to said handle in selective positions of movement therealong.

6. A tool as set forth in claim 1 in which said blade assembly includes a generally cylindrical blade holder and a bore in said assembly for receiving said holder, a manually engageable knob threadedly engaged with said holder whereby rotation of said knob effects axial movement of said holder in said bore.

7. A tool as set forth in claim 6 in which means are provided for restraining rotation of said holder during knob rotation while permitting said axial movement, and means extending radially outwardly from said holder for selectively varying the rotational disposition of said holder relative to said bore independent of said knob rotation and independent of the axial position thereof.

8. A tool as set forth in claim 7 in which said last named means includes a bushing rotatably joumalled in said bore and having an inwardly directed lug, said holder having an axially extending peripheral groove receiving said lug.

9. A tool as set forth in claim 8 in which said bushing is provided with a manually engageable radially extending element for effecting holder rotation.

10. A tool as set forth in claim 9 including means for releasably locking said latter element on said assembly.

11. A tool as set forth in claim 1 in which said blade assembly includes a blade holder rotatably mounted therein, and said last named means including a member connected to and extending radially outwardly from said holder for selectively rotating the holder in said assembly to provide an infinite number of angular dispositions of said blade.

12. A tool as set forth in claim 11 including means for locking said radially extending member in desired positions. 

1. A tool for removing insulation from an insulated conductor cable comprising cable engaging means having spaced elements engageable with circumferentially spaced portions of a cable positioned therebetween, said elements permitting rotation of a cable therein, a blade assembly overlying said engaging means including a blade having a cutting edge, said blade extending generally normal to the axis of a cable positioned on said engaging means, means in said assembly for selectively moving said blade in a linear direction along the blade length, and for locking said blade in selected depths of insulation penetration, means in said assembly for changing the angular disposition of said blade about an axis defined by said lineal blade movement independent of said linear blade moving and locking means and while said blade is engaged with the insulation, and means in said assembly for locking said blade in selected positions of angular disposition.
 2. A tool as set forth in claim 1 in which means are provided for selectively moving said elements from and towards each other for accommodating different diameter cable sizes.
 3. A tool as set forth in claim 1 in which said elements include a plurality of angularly related planar surfaces extending generally normal to said blade.
 4. A tool as set forth in claim 3 in which a pair of said surfaces defines a generally V-shaped configuration and another of said surfaces overlies the same and has an end portion terminating inwardly of the corresponding end portions of said pair of surfaces, and said blade extending downwardly from adjacent said first mentioned end portion in overlying relation to said corresponding end portions.
 5. A tool as set forth in claim 1 including a manually engageable handle extending longitudinally from said cable engaging means in general parallel relation to said blade, at least one of said elements being carried on said handle for movement therealong, and means for releasably securing at least one of said elements to said handle in selective positions of movement therealong.
 6. A tool as set forth in claim 1 in which said blade assembly includes a generally cylindrical blade holder and a bore in said assembly for receiving said holder, a manually engageable knob threadedly engaged with said holder whereby rotation of said knob effects axial movement of said holder in said bore.
 7. A tool as set forth in claim 6 in which means are provided for restraining rotation of said holder during knob rotation while permitting said axial movement, and means extending radially outwardly from said holder for selectively varying the rotational disposition of said holder relative to said bore independent of said knob rotation and independent of the axial position thereof.
 8. A tool as set forth in claim 7 in which said last named means includes a bushing rotatably journalled in said bore and having an inwardly directed lug, said holder having an axially extending peripheral groove receiving said lug.
 9. A tool as set forth in claim 8 in which said bushing is provided with a manually engageable radially extending element for effecting holder rotation.
 10. A tool as set forth in claim 9 including means for releasably locking said latter element on said assembly.
 11. A tool as set forth in claim 1 in which said blade assembly includes a blade holder rotatably mounted therein, and said last named means including a member connected to and extending radially outwardly from said holder for selectively rotating the holder in said assembly to provide an infinite number of angular dispositions of said blade.
 12. A tool as set forth in claim 11 including means for locking said radially extending member in desired positions. 